Apparatus for pressing slurries



Feb. 15, 1966 T. o. QUINN APPARATUS FOR PRESSING SLURRIES 2 Sheets-Sheetl Filed Sept. 24, 1962 To sL/cT/o/v D/SCHA PGE SLL/FRY FEEDER w R n .0 0W M t M me D N0 i m E0, M 2,5 2 Mms; 2 6 2 32x22 0 in 34mg 2 2 0 2 $6722ow91 w k u 2 22 i4 T x ME 7 S 2/ my m 2 2 Z i /O F6 nl oww ETE CNP 9RER 2 @my 2/ soc ATTORNEYS Feb. 15, 1966A l 1.0.QUINN 3,234,598

APPARATUS FOR PRESSING SLURRIES Filed sept. 24, 1962 2 sheets-sheet 2 EINVENTOR Thomas 0. 00in/7 ATTORNEYS United States Patent O 3,234,598APPARATUS FOR PRESSING SLURRIES Thomas 0. Quinn, Valparaiso, Ind.,assignor to Indiana General Corporation, Valparaiso, Ind., a corporationof Indiana Filed Sept. 24, 1962, Ser. No. 225,799 8 Ciaims. (Cl. 18-16)This invention relates generally to an improved apparatus for pressingslurries and particularly to an improved pressing arrangement forforming a slurry of ferrite material into a desired compact form in theprocess of forming such ferrite material into permanent magnet units orthe like.

In one form of apparatus for pressing slurries a die is provided havinga pressing chamber of configuration to form the desired part. The die isopen at one end to allow feeding of the slurry into the pressingchamber. After the slurry is in the pressing chamber, the open end ofthe die is closed by hydraulically moving a filter head against the openend of the die. A die punch is provided in the die for acting on theslurry in the pressure chamber and a hydraulic cylinder actuatorexternal of the die is mechanically linked to the die punch so that byapplying pressure to the actuator the die punch is moved toward thefilter head to force the fluid in the slurry out of the pressing chamberthrough the filter head and thus to form a compacted mass which isfurther treated in the usual manufacturing process.

There are many disadvantages to such an apparatus. For example, themechanical coupling between the hydraulic cylinder actuator and the diepunch must be extremely accurately aligned to operate. Any misalignmentaffects the nished part or jams the mechanism causing failure thereof.Also the clearance between the punch and the die even though sealed withgaskets permits the fiuid in the slurry due its high hydrostaticpressure to bleed past the seals with resultant ill-effects on thefinished part and on the area surrounding the press. A furtherdisadvantage is a limitation placed on the length of stroke permittedfor the punch in the die as a result of the mechanical limitationscreated by the limited stroke of the hydraulic cylinder actuator. Also,since the hydraulic actuator is fixed in size, the pressure supplied tothe actuator for driving the punch in the d-ie must be varied with eachdifferent die to get the desired pressure on the slurry.

It is, therefore, a principal object of the present invention toovercome the above noted disadvantages and toprovide an improved slurrypress.

A further principal object of this invention is to provide an improvedwet press wherein the hydrostatic pressure of the iiuid in the slurry isprevented from seeping past the piston by a substantially balancedhydrostatic pressure of the actuating fiuid on the opposite side of thepiston.

It is another important object of this invention to simplify theconstruction of the die and actuating mechanism of a slurry press byeliminating the mechanical hook-up between the driving cylinder and thedie punch.

It is a further object of this invention to provide an improved slurrypress of a design such that dies having slurry chambers of differentconfigurations may lbe properly actuated with the same fluid pressure.

Another object of this invention is to provide an im- ICC proved slurrypress wherein the only limitation on the length of stroke of the diepiston is the length of the die itself.

Still another object of this invention is to provide an improved slurrypress that is simpler in operation, has

fewer operating parts, is easier to repair and maintain, isv

cheaper to construct, and is more efiicient and therefore moreeconomical to operate.

Other objects, features and advantages of the present invention will beapparent from the following detailed description taken in connectionwith the accompanying drawings, in which:

FIGURE 1 is a somewhat diagrammatic elevational view illustrating aslurry pressing arrangement in accordance with the present invention;

FIGURES 2 and 3 are vertical sectional views of the die assembly ofFIGURE 1, FIGURE 2 illustrating the position of the die piston prior tothe pressing operation and FIGURE 3 illustrating the position of thepiston member in ejecting the compacted mass from the die;

FIGURE 4 is a vertical sectional View illustrating a modified pressutilizing spring actuated retraction of the die piston member;

FIGURE 4A is a cross sectional view taken along the line 4A-4A in FIGURE4; and

FIGURE 5 is a vertical sectional view illustrating a,

further modified form of pressing apparatus.

Referring first to the embodiment of FIGURES 1, 2 and 3, there isdisclosed a fixed framework 10 having a hydraulic actuator mechanism 11secured thereto for vertically moving a table 12 on which a die assembly13 is carried. As indicated diagrammatically in FIGURE 1,

the hydraulic actuator 11 may have a cylindrical cham-i ber 15 with apiston member 16 movable therein which is linked by means of a pistonrod 17 to the support table 12. To raise the table 12 hydraulic pressureis applied to the hydraulic line 19 connecting with the lower chamber ofactuator 11 while fiuid is drained from the upper chamber of thecylinder via hydraulic line 20. Hydraulic pressure may be applied to theline 20 communicating with the upper chamber of the cylinder 11 toreturn the table 12 to its lower position shown in FIGURE l.

As best seen in FIGURE 2, the die assembly 13 includes a die casinggenerally designated by the reference numeral 22 which has interiorsurfaces such as cylindrical surfaces 23 and 24 defining an elongated`interior space within the casing. The casing is also provided with anopen upper end as indicated at 25 which provides access to a presingchamber 27 within the casing. The pressing chamber 27 will have a crosssectional configuration corresponding to the cross sectionalconfiguration to be formed by the press. For example, where an annularor ring shaped configuration is to be formed a core member indicatedgenerally at 29 extends axially of the casing and is provided with anexterior cylindrical surface 30 defining a boundary of the pressingchamber 27.

As illustrated in FIGURE l, the slurry t-o be compacted such as bariumferrite slurry utilized in forming permanent magnets of the ceramictype, may be supplied to the pressing chamber 27 Via the open end 25 ofthe die casing 22 by means of a suitable conduit 32 from a slurry feeder33 which may take the form disclosed in U.S. Patent No. 2,877,929 issuedMarch 17, 1959.

When the slurry has been fed into the pressing chamber 27, the conduit32 is removed, and the hydraulic actuator 11 is supplied with pressurefrom the hydraulic pressure control unit indicated at 35 in FIGURE 1 toraise the die assembly 13 and press the open end 25 of the die casing 22against a filter head assembly generally designated by the referencenumeral 37. The filter head assembly may include a suitable filter paper38 and a filter block 39 having suitable drainage openings such asindicated at 40 aligned with the pressing chamber 27 and leading to adischarge passage 42 which may be connected to a suitable suction devicefor removing fluid from the collection chamber 43. The filter paper 38may be held in the position shown in FIGURE 1 by any suitable means ormay be placed on the end 25 of casing 22 after conduit 32 is displacedtherefrom. The filter head assembly is fixedly secured to the frame soas to be rigidly fixed relative to the cylinder 11; The hydraulicpressure control means'35 may supply fluid under pressure to thehydraulic line 19 continuously during the slurry pressing Aoperation soas to insure sealing of the open end Vof the die casing 22 against thefilter head assembly 37.

Also during the pressing operation, direct current may Ibe supplied fromsource 44 to a helical winding indicated at 45 by means of a switch 46to produce a vertically directed magnetic orienting field in thepressing chamber '27.

In FIGURE 2 the barium ferrite `slurry (not shown) is sealed in thepressing chamber 27 `by means of the filter paper 38 and filter block 39in conjunction with the pressure applied by the ta'ble 12 at the lowerend of the die assembly. The hydraulic pressure control of FIG- URE 1includes a hydraulic pressure source 47 which may supply hydraulic-fluidunder pressure to both lines 48 and 49 indicated in FIGURES 1 and 2 toinitiate .a pressing operation. As seen in FIGURE 2, a hydraulic fluidapplied to the line 48 enters an actuating chamber 50 `by means of aninlet port 51 in casing member 52 of casing 22 and fluid pressuresupplied to line 49 is applied to an actuating chamber S4 through aninlet port 55 of casing member 52. An actuating piston 55 forms auni-tary part of the die plunger assembly within the die casing 22 andas seen in FIGURE 2 has a greater cross sectional area exposed to thelower 4actuating chamber S4 than t0 `the upper actuating chamber 50.Thus with equal pressures in the two chambers, there is a net upwardforce on the plunger assembly 60 tending to compress the slurry in thepressure chamber 27. The lower end of the die casing 22 is closed bymeans of a suitable base member 62 `secured lto the casing member 52 bymeans of screws such as indicated at 64. The surface 65 of the base 62which engages the lower surface of the actuating piston 55 may begrooved as indicated at 66 to provide fluid communication Ibetween theactuating chamber portion 54 and actuating chamber portions 68 and 69.The fluid actuating pressure is thus communicated to the region at thelower side of the pressing piston 72 which is a unitary part of theplunger assembly 60. The pressure at the region 70 substantiallycorresponds to the hydrostatic pressure of the slurry in the pressingchamber 27 during the pressing operation so as to tend to preventleakage between the pressing piston member 72 and the surface 30 of thecore 29.

The actuating chamber 50 communicates with a region 75 immediatelyadjacent the outer perimeter of the pressing piston member 72 lby meansof passages 77 in an adjustable stop member of ring configuration. Thelower surface 81 of the stop member 80 abuts the upper surface ofactua-ting piston member 55 as indicated in FIG'URE 3 at the end of thestroke of the die plunger assembly 60. Since the pressure in the chamber50 is the same as the pressure in the chamber 54, the pressure in theregion 75 adjacent the outer perimeter of the pressing piston member 72is comparable to the hydrostatic pressure of the yslurry within thepressing chamber 27 to tend to prevent leakage between the pressingpiston member 72 and the internal surface 23 of thedie casing 22.

With a given pressure applied to the actuating chambers 50 and S4, theupper surface 85 of piston member 72 will be driven to a position asindicated by the dash line 85a in FIGURE 3 with the die assembly 13pressing against the filter head 37 under the impetus of the hydraulicactuator 11. When, however, uid pressure is remove-d from the line 19 ofthe actuator 11 and the table 12 is retracted to a position such asindicated in FIGURE 1, the fluid pressure in the chamber 54 will drivethe actuating piston member 5S against the stop surface 81 which willmove the upper surface 85 of pressing piston member 72 to the positionshown in solid outline in FIG- URE 3 ejecting the compacted mass 90 offerrite material which is indicated in FIGURE 3. The hydraulic pressuremay be removed from actuating chambers 50 and 54 before table 12 isretracted, so that piston member 72 remains substantially at thepressing position 85a during lowering of table 12. This avoids exertingsubstantial forces on the mass during the ejection step when the mass isnot completely laterally supported by surfaces 23 and 30.

With this mode of operation, when the table has been lowered to theposition shown in FIGURE 1, pressure is reapplied to chambers 50 and 54to move the piston member 72 from the pressing position indicated at 85ato the ejecting position shown in solid outline in FIGURE 3. The mass 90will have a ring shape in conformity with the cross section of thepressing chamber 27 and will have a thickness corresponding to thespacing between the dash line 85a and the upper surface 91 of casing 22.The mass 90 may be removed by sliding it laterally over the surface 91and onto a suitable receiving surface which is flush with surface 91 atthe time the mass 90 is removed from the die. This operation may becarried out by a suitable mechanical device where the pressing procedureis carried out automatically. When it is desired to retract the dieplunger assembly 60 to -the initial position shown in FIGURE 2, thehydraulic valve member 94 is turned through 120 in the clockwisedirection as seen in FIGURES 2 and 3 to connect the line 49 to drainwhile pressure from the source 47 is still 'being supplied via line 48to the chamber 50.

For convenience of manufacture and assembly, the various majorcomponents which have been referred to r are preferably formed of anumber of individual parts which will now be briefiy referred to by wayof example and not of limitation.

The die casing 22 includes an upper tubular member 180 having a tubularlining 101 providing the interior surface 23. The casing 22 furtherincludes a cover part 194 which is secured to the part 100 by means ofscrews and is secured to the lower member 52 of the casing by means ofscrews 107. Suitable seals are provided between the various parts of thecasing 22 to provide a iiuid tight interior space. The stop member 80which is considered as part of the casing 22 is threadedly engaged withthe cover member 104 so as to be axially adjustable for adjusting theupper limit of travel of the plunger assembly 6i). The surface 85 issubstantially flush with surface 91 and preferably slightly thereabovein the ejection position of the plunger assembly shown in FIG- URE 3.

The core assembly 29 includes an upper cylindrical rod having a tubularliner 111 providing the exterior surface 30. The rod 11) has a threadedportion 114- secured therewith and threadedly engaged with a lower coremember of cylindrical configuration. The lower member 115 is secured ina recess in base 62 by means of screws 117. Suitable sealing means areprovided b'e'tween casing members 52 and the base 62 and between thebase 62 and the lower core member 115 to prevent leakage from theactuating chamber 54.

The plunger assembly 60 includes a lower tubular member threadedlysecured to the pressing piston member 72 at its upper end and threadedlysecured to the actuating piston member 55 at its lower end.

Gaskets are indicated at 120 and 121 between the outer perimeter of thepressing piston member 72 and the die surface 23 and further gaskets areindicated at 122 and 123 between the inner perimeter of the pressingmember 72 and the die assembly surface 3l] for preventing the slurryfrom escaping back into the actuating chambers 50 and 54 and to preventthe hydraulic fluid in the actuating chambers from eroding the cornersof the compressed material in the pressing chamber 27. During normalpressing of the slurry, the difference in the hydrostatic pressure ofthe slurry and the hydrostatic pressure of the hydraulic fluid in theactuating chambers 50 and 54 is relatively low so that no leakage pastthe gaskets will occur. The only time the seals are really necessary iswhen the piston member 72 is in the fully advanced position indicated bythe dash line 85a in FIG- URE 3 and before the pressed material 90 isremoved from the die. The gaskets 120-123 may comprise rings having across section with four lobes which lobes are seated in the respectivefour corners of the recesses in the pressing piston member 72. Anadditional sealing ring is indicated at 125 at the outer perimeter ofthe actuating piston member 55 which travels on the die surface 24. Itwill be observed that the plunger assembly 60 is entirely confinedwithin the interior space of the die casing 22 so as to form what willbe termed a free or floating type piston. Such a piston is in contrastwith the type wherein the die plunger has a stem extending through theend wall of the die which stem is coupled to a hydraulic actuator at theexterior of the die assembly. In such a case the die plunger is providedwith a force transmitting actuating stern extending to the exterior ofthe die casing and would not constitute a free or floating type ofpiston arrangement.

Where a magnetic orienting eld is applied vertically in the pressingchamber 27, certain of the parts should be of non-magnetic materialwhile others may be or preferably are of magnetic material. A suitablechoice of materials is indicated in the following table:

Practical hydraulic circuits would of course include means forpreventing the formation of air pockets in the actuating chambers duringflow of hydraulic fluid therefrom, and the term drain is used herein asincluding such an air exclusion means.

Summary of operation for the embodiment of FIGURES 1-3 In the embodimentof FIGURES 1 through 3, a slurry of barium ferrite material or the likeis first fed to the pressing chamber 27, FIGURE 2, from a slurry feeder33, FIGURE l, via a conduit 32. The conduit 32 is then removed andhydraulic pressure applied to the hydraulic line 19 to raise the table12 together with the die assembly 13 until the open end 25 of the diecasing 22 is pressed against the filter head 37, FIGURE 1. The hydraulicpressure source such as indicated at 47 in FIG- URE 2 is then activatedas by opening a shut-olf valve 126 to supply the same hydraulicactuating pressure via lines 48 and 49 to the actuating chambers 50 and54 of the die casing 22. The difference in area of the plunger assembly60 exposed to the respective actuating chambers 51) and 54 results indriving of the plunger assembly 60 in the upward direction andpreferably compressing the slurry in the pressing chamber 27 with apressure substantially equal to the actuating pressure. Water from theslurry is forced through the lilter paper 38 and through the passages 40in the filter block 39 to a suitable discharge or drain means. The valueof pressure supplied to the actuating chambers may be the sameregardless of the cross sectional configuration of the part to be formedsince the difference in the effective plunger areas exposed to chambers50 and 54 may always be equal to the cross sectional area of thepressing chamber 27 regardless of its cross sectional conliguration.

The pressure supplied to the actuating chambers 50 and 54 is such as tomove the pressing piston member 72 `from the position shown in FIGURE 2Vto the pos-ition indicated yby the dash line a in FIGURE 3. Thismovement of the piston member 72 results in the formation of a compactmass as indicated at of barium ferrite material. The mass 90 may beejected from the die by removing actuating pressure from chambers 50 and54 as by closing valve 126, FIGURE 3, and lthen supplying hydraulicpre-ssure to the line 20 shown in FIGURE 1 While connecting line 19 todrain to lower the .table 12 to the retracted position shown in FIGUREl. Thereafter valve `126, FIGURE 3, is again opened t-o supply theactuating pressure to chambers 50 and 54 so as to move the plungerassembly 60 from the pressing position Iindicated by dash line 85a tothe ejecting position shown in solid outline in FIGURE 3 with the lowersurface of the compacted mass 90 substantially ush with the die uppersurface 91, and preferably slightly .thereabove To retract the plungerassembly 60 to the position shown in FIGURE 2, valve 94, FIGURES 2 and3, may be turned in .the clocklwise direction to connect the -lolweractuating chamber 54 to drain While the upper chamber 50 still receivesfluid pressure from the source 47.

It will be apparent that multiple pressing chambers may lbe formed in asingle die casing and that independently movable pressing piston membersmay lbe movable in the respective pressing chambers to form multipleparts in the same die casing. The pressing piston members may utilizethe same actuating chamber or chambers. FIG- URES 2 and 3 may beconsidered as illustrating such a modification by considering that thepressing chamber 27 is divided into semi-circular chambers and -byconsidere ing that the plunger assembly 60 -is divided into two separateindependently movable half sections each individually actuated by theactuating chambers 50 and 54 in which the two half sections `aremovable. By this means the two plunger sections would be advanced attheir oiwn rate to compress the material in the respective pressingchamber sections and such an arrangement would allow for differences inthe pressing rates `of the slurries in the two pressing chambersections.

Where a multi-piston external hydraulic actuator is utilized foractuating a plurality of plunger mechanisms, if uneven amounts of-slurry are fed into the respective die lcavities the balance of theactuator is upset and improperly pressed parts result. By utilizingseparate free floating plun-ger assemblies in a common die casing asjust described, each plunger section may advance at its own rate withoutaffecting the advance of the other plunger section.

It will be yobserved that the pressure supplied to the actuatingchambers 50 and 54 determines the pressure applied to the slurry; thatis, the pressure exerted by the piston member 72 on the slurry issubstantially identical to the pressure supplied by the pressure source47 to the actuating chambers 50 and 54. With a multiple cavity die, thepressure applied to each cavity would be identical to the actuatingpressure and would be selected to give the proper cha-racteristics ofthe. resultant compacted mass such as indicated at 90 in FIGURE 3. Thesame hydraulic pressure source supplying the proper pressing pressurewould then be applicable to dies of any desired configuration so long asthe required pressing pressure on the slurry lwere the same. In otherwords, the pressing chamber 27 may have any desired cross sectionalconiiguration in the embodiment of FIGURES 2 and 3 without changing thepressure required from the. hydraulic pressure source 47.

Description of the embodiment of FIGURE 4 FIGURE 4 illustrates amodified pressing assembly utilizing only a single actuating chamber 140and returning the pressing piston member 141 to its initial position bymeans of a compression spring '143. The pressing assembly comprises adie casing 145 having an interior space extending Ifor the length of thedie assembly and defined by interior surface port-ions 147, 148, 149 and150. The die casing is formed by an upper member 150 having a tubularliner 151 and a tubular liner 152 prolviding the interior surface 147.The upper casing member 150 is secured to an intermediate member i154 bymeans of screws 155, the member `154 providing the interior surfaceportions 148 and 149. A lower tube member 156 is secured to the lowerend of the intermediate member 154 by means of screws 157, and the endwall |159 of member '156 rests on the table 12 for pressing of the openupper end -160 of the casing against the filter head generallydesignated by the reference numeral 37 and illustrated in greater detailin FIGURE l. The die casing may also be considered as including a plate1263 which is of disk coniiguration and is clamped between the members150 and 154 by the screws 155. The. plate y163 mounts a central coremember 165 which is secured centrally of the plate 163 by means of ascrew 167. The plate 163 has a pair of arcuate slots 168 and 1619 asshown in FIGURE 4A which receive the bi-furcated end portion 170 of thepressing piston lmember 1411. The radial dimension of the. slots E163and 169 may be substantially Igreater than the radial dimension of theend portion 170 of member 141 t-o provide uid communication through theslots to the region adjacent a peripheral shoulder portion .171 of lowersurface portion 172 of the piston member 141. The peripheral shoulder171 has an inner circular margin of diameter equal to the outsidediameter of end portion `170 and has an outer circular edge indicated at1710i in FIGURE 4A equal to the outside diameter of piston member 141.As the piston member 141 moves upwardly the inner surface of fliner l152and then of liner 151 is progressively exposed to the pressure ofchamber 140 at the space Ibelow the entire perimeter of shoulder portion17:1 of the piston member 141. The piston member 141 `is illustrated asbeing provided with sealing rings which may be of the same type asdescribed in connection with FIGURES 2 and 3.

A bolt 175 may be secured to the lower end 170 of the piston member 141by means of a cup member 176 threaded onto end |170. A threaded collarmember i178 is threaded onto the lower end. of the bolt 175 and lockedthereon by means of a nut 179 to serve as an abutment for engagementwith the compression spring 143 which is thus effective to urge thepiston member 141 downwardly toward the initial posi-tion illustrated inFIGURE 4. A washer l182 may be interposed between the cup member 176 anda seating surface 183 of intermediate member 154, and suitable means maybe -provided for insuring fluid communication at all times between theactuating chamber `140 and the spring chamber 185; for example, thesurface 183 :may be grooved as indicated at 187. The surface 1172including shoulder portion 1171 at the lower side of piston member 141may actually be spaced slightly above the upper surface of plate 163when cup 176 and washer 182 are bottomed against seating surface 183.

The exterior surface 190 of core member 165 together with the interiorsurface 147 of the liner 151 and the upper surface 192 of piston member141 defines a pressing chamber 194 receiving a barium ferrite slurry 195which is to be compressed `as in the preceding embodiment. There isfluid pressure communication between the actuating chamber 140 and thelower surface portion 197 of piston member 141 through the arcuate slots1,68 and 169 so that there is fluid in the region 198 at the samepressure as in the actuating chamber 140.

As diagrammatically indicated in FIGURE 4, hydraulic pressure from apressure source 201 is supplied via line 202 and an inlet passage 203 inmember 154 to the actuating chamber 140 to apply actuating pressure tothe piston member 141 at its lower surface portions 172 and 197 sorthatthe piston member 141 applies a pressure to t-he pressing chamber 194which is substantially identical to the pressure supplied to theactuating chamber 140 from the source 201 as in the previous embodiment.The piston member 141 is actually of the free floating type as in theprevious embodiment since the bolt 175 does not transmit actuating forceduring the working stroke of the piston but is simply a device forreturning the piston to its initial position. It will be observed thatthe maximum distance through which the pressing piston 141 may be movedis slightly greater than the maximum length of the pressing chamber 194,so that the compacted mass of barium ferrite (corresponding to thatindicated at 90 in FIGURE 3) may be ejected from the pressing chamberafter the upward hydraulic force is removed from the table 12 and theopen end 160 of the casing 145 is retracted from the filter head 37.With the filter head 37 closing the open end 160 of the casing, andpressure supplied to the line 202, the piston member 141 will compressthe slurry 195 to a predetermined thickness `substantially less than thelength of the pressing chamber 194 and will stop at a pressing positioncorresponding to that illustrated in FIGURE 3 by the dash line a.

After `the compacted mass has been ejected in the same manner asillustrated in FIGURE 3, the piston member 141 is returned to theinitial position shown in FIGURE 4 by rotating valve 210 through an`angle of in the clockwise direction to connect the line 202 to drainand allow the compression spring 143 to ret-urn the piston member 141.

In the embodiment of FIGURE 4, the actuating pressure o-f chamber iscommunicated to the surfaces 171 and 197 at the outer and innerperimeters of the piston member 141 so as to tend to equalize thepressures at the leading and trailing sides of the piston member 141completely about the inner and -outer perime-ters of the piston memberduring the pressing operation. Thus, during normal pressing of theslurry, the difference in the hydrostatic pressure of the slurry 195 andthe hydrostatic pressure of the hydraulic fluid in the actuating chamber140 is relatively low so that no leakage occurs past the gaskets such asindicated at 211-214. The only time the gaskets are really necessary iswhen the piston is in the fully advance-d position corresponding -to theposition 85a in FIGURE 3 and before the pressed mass of barium ferriteor the like is removed from the die.

Where a vert-ical orienting field is applied to pressing chamber 194 bymeans of the winding 45 shown in FIGURE 1, the magnetic character of thematerial used 9 for the various p-arts shown in FIGURE 4 may be asfollows:

Summary of operation of the embodiment of FIGURE 4 In FIGURE 4, theslurry 195 is supplied to the pressing chamber 19'4 -by means of theconduit 32 from the slurry feeder 33 exactly as indicated in IFIGURE 1.-FIGURE 4 indicates the case where filter paper 38 isplaced on thecasing 145 after the slurry is supplied to the pressing chamber, butsuitable means may be provided for holding the filter paper against thelower end of the filter block 39 as in FIGURE 1, if desired. Thereafter,table 12 is actuated to press the open end 160 of the casing 145again-st the filter head assembly 37 as in the preceding embodiment.Hydraulic pressure source 201 then supplies hydraulic fluid at apredetermined pressure to the chambers 140, 185 and 198 to move thepiston member 141 upwardly against the action of the com-pression spring143. The pressure exerted by the piston member 141 on the slurry 195 issubstantially identical to the pressure supplied to the actuatingchamber 140. The pressure exerted on the pressing chamber 194 is,however, somewhat less than the pressure supplied to the actuatingchamber 140 because of the action of the compression spring 143. Theforce exerted -by the spring 143 can, however, be relatively small sinceits only function is to return the piston 141 to its initial positionafter the valve 210 has connected the actuating chamber 140 to drain.

When the slurry 195 has been formed into a compact mass in the same wayas illustrated in connection with FIGURE 3, valve 210 may be turnedthrough 60 to shut-off the supply of uid pressure to the actuatingchamber 140. Thereafter rthe table 12 is retracted and valve 210returned to the position shown in FIGURE 4 so that actuating pressure inchamber 140 will cause the piston member 141 to eject the compacted massfrom the pressure chamber 194. The stroke of the piston member 141 issuch that the upper surface thereof 192 reaches a level substantiallyflush with and preferably slightly above the open end 160 in t-he sameway -as explained in connection with FIGURE 3 `for the previousemb-odiment.

To return the piston member 141 to its initial position illustrated inFIGURE 4, valve 210 is turned through 120 in the clockwise directionwhereupon spring member 143 returns the piston member 141 to theposition shown in FIGURE 4.

It will be apparent that a multiple cavity die in accordance with theprinciples of FIGURE 4 may be constructed wherein the pressing pistonsfor the respective pressing chambers operate independently of each otherbut receive the same actuating pressure. Individual spring return meanscan be utilized with each individually acting piston member, forexample.

Descrip-tion of the embodiment of FIGURE 5 In the embodiment of FIGURE5, the hydraulic actuator 11 of FIGURE 1 is omitted and in its place aretainer member 220 is threadedly engaged with the open end 221 of thedie casing 222 so as to clamp the filter head assembly 224 inclosingrelation to the pressing chamber indi- 10 cated at 226. Theretainer member 220 is provided with oppositely projecting arms 229 and230 which are convienently grasped manually in threading the retainingmember 220 onto the end of the die casing 222.

The Iilter head assembly 224 has been illustrated as including a filterring 232 having suitable passages therein such as indicated at 233 inalignment with `the pressing chamber 226. A suitable filter paper ofcorresponding ring configuration is indicated at 235 which is retainedin closing relation to the open end of the die casing 222 by means ofthe filter ring 232 and retaining member 220.

The casing 222 is shown as being made up of parts 240 and 241 threadedlyengaged as indicated at 242. The die assembly further comprises acentral core 245 including core members 246 and 247 secured together bymeans of a screw 248 and secured to the closed end 250 of casing member241 by means of a screw 252. The core members 246 and 247 are providedwith cylindrical holes which are in alignment with cylindrical holes inthe base 250 of the casing member 241. A water-cooled electricalconductor 257 has straight length portions 25761 and 257b extending inthe aligned holes and joined in space 222a by a curved length portion257C. The conductor 257 may be connected with a direct current source258 by means of a switch 259 for setting up an orienting magnetic fieldin pressing chamber 226 during the pressing operation.

The interior surface 270 of the die casing 222 and the interior surface271 of the central core assembly serve .to define the annular pressingchamber 226 which receives a barium ferrite slurry (not shown) as in thepreceding embodiments. Sealing rings are indicated at 276 and 277 forsealing off the pressing chamber 226. A piston member 280 is indicatedat its initial position and may be provided with sealing rings 281-284as in the preceding embodiments. An actuating chamber is indicated at290 which is in fluid communication with hydraulic pressure source 291via line 292, valve 293, line 294 and inlet opening 295 in casing member241. The actuating chamber 290 communicates with the lower end of thepiston member 280 by means of an annular clearance space 297 so thatactuating fluid pressure is applied at the rear or lower side of thepiston member 280 at both the inner and outer perimeter thereof. As thepiston member 280 is driven upwardly in the pressing chamber 226, wateris driven through the filter paper 235 and through the passages such as233 to a collection chamber 302 from which water is withdrawn by meansof a passage 303 in the retainer member 220. The passage 303 may lead toa downwardly extending hose so that water is removed from the filterhead at the end of the pressing operation by means of a siphoningaction. A similar arrangement may be used in FIGURE 1 for removing waterwhich is not forced from the filter head by the hydrostatic pressureduring the pressing operation.

After the slurry material has been compacted into the desiredconfiguration, the valve 293 may be turned through 60 to shut off thesupply of hydraulic pressure to the actuating chamber 290. Thereafterthe handles 229 and 230 may be manually operated to rotate the retainingmember 220 in the direction to unscrew the same from the top end of thecasing 222. The valve 293 is then returned to the position shown inFIGURE 5 to connect the source 291 to the actuating chamber 290. Theactuating pressure is then sufficient to drive the cornpacted mass outof the pressing chamber 226 in the same manner as illustrated in FIGURE3. When the piston member 280 is driven to a position with its uppersurface substantially liush with the surface of end 221 of the casing222, the valve 293 is actuated to shut off pressure to the actuatingchamber. Thereafter, the compacted mass of barium ferrite may be removedas by sliding it laterally over the surface of end 221 of the casing andonto a supporting surface substantially flush therewith. The pistonmember 280 may be returned to its initial position Part Character ofName of Part Reference Material Num eral Retaining member 220Non-magnetic. Filter ring 232 Do. Upper casing part.- 240 Magnetic.Lower easing part 241 Do. Upper core member 246 Do. Lower core member247 Do. Piston member 280 N on-magnetic.

Summary of operation of the embodiment of FIGURE In the embodiment ofFIGURE 5, the barium ferrite slurry is supplied to the pressing chamber226 by removing the retaining member 220 manually together with thefilter head assembly 224. After lling of the pressing chamber 226 withthe barium ferrite slurry, the filter head 224 is reapplied and theretaining member 220 threaded onto the upper end of the die casing 222to clamp the filter head in position. Orienting current may be suppliedto conductor 257 by closing switch 259. Hydraulic pressure from source291 is then supplied to the actuating chamber 290 which transmitspressure to the lower side of the pressing piston member 280 to drivethe piston member 280 in the upward direction. The piston member 280 isof the lfree or floating type as in the preceding embodiments with theactuating fluid pressure acting directly at one side thereof and theopposite side thereof (the upper side) acting on the slurry. When thepiston member 280 has reached its final position a predetermineddistance below the filter head 224, the hydraulic pressure may be shutoff by turning valve 293 through 60, for example. The `retaining member220 then may be manually unthreaded from the die casing 222 and thehydraulic pressure reapplied to the actuating chamber 29@ to drive thecompacted mass of barium ferrite out of the pressing chamber 226. Whenthe compacted mass has been suitably ejected, valve 293 is turned to anoff position until the mass has been removed. Thereafter, valve 293 ispositioned 120 counterclockwise from the position shown in 'FIGURE 5 toconnect the actuating chamber 290 to drain. The piston member 280 may bereturned to its initial position manually, for example by means of asuitable tool inserted into the pressing chamber 226.

As in the previous embodiments, the pressing chamber and piston member280 may be considered as being split into two separate sections to formtwo separate compacted masses so as to constitute an illustration of amultiple cavity die having a com-mon actuating chamber receiving acommon actuating pressure.

It will be apparent that many modifications and variations may beeffected without departing from the scope of the novel concepts of thepresent invention.

I claim as my invention:

1. A slurry pressing devi-ce comprising a die assembly having cavitydefining means providing an elongated die cavity of a cross sectionalcontour corresponding to the cross sectional contour of a mass to befor-med,

a filter head assembly for closing said cavity at one end thereof,

a free floating plunger assembly having pressing means of crosssectional contour movably fitting in said cavity of said die assemblyand having one side thereof defining a movable boundary of a slurrypressing cha-mber of said cavity and said plunger assembly being movabletoward said one end of said cavity to compress a slurry in said pressingchamber and drive fluid `from the pressing chamber through said filterhead assembly,

means providing for loading of a slurry into said pressing chamber,

said die assembly having actuating chamber defining means rigidlyconnected with said cavity defining means and providing an actuatingchamber within said die assembly for containing fluid under pressureacting on said plunger assembly to drive said plunger assembly towardsaid filter head assembly, and

means providing for delivery of fluid under predetermined pressure tosaid actuating chamber to compress the slurry in said pressing chamberto a predetermined configuration,

said actuating chamber defining means providing a second actuatingchamber within said die assembly for containing uid under pressureacting on said -plunger assembly to drive said plunger assembly awayfrom said filter head assembly, the area of said plunger assemblyexposed to uid pressure in said second actuating chamber beingsubstantially less than the area of said plunger assembly exposed tofluid pressure in the first-mentioned actuating chamber, and saiddelivery means delivering iiuid -under said predetermined pressure toboth said first mentioned and said second actuating chambers duringpressing of the slurry in said pressing chamber.

2. The device of claim 1 with the difference between the area of -saidplunger assembly exposed to said fluid pressure in said first mentionedand said second actuating chambers being substantially equal to thecross sectional area of said pressing chamber.

`3. The device of claim 1 with said. pressing means having an oppositeside opposite said one side thereof, said die assembly including a coremember extending centrally of said `die cavity, said pressing meansbeing in slidable relation to the exterior surface of said core member,and means providing uid communication between the first mentionedactuating chamber and said opposite side of said pressing means at theinner perimeter thereof, and means yproviding fiuid communicationbetween the second actuating chamber and said opposite side of saidpressing means at the outer perimeter thereof.

4. A slurry pressing device comprising a die assembly having cavitydefining means providing an elongated die cavity of a cross sectionalcontour corresponding to the cross sectional contour -of a mass to beformed,

a filter head assembly for closing said cavity at one end thereof,

a free floating -plunger assembly having pressing means of crosssectional contour movably fitting in said cavity of said die assemblyand having one side thereof defining a movable boundary of a slurrypressing chamber of said cavity and said plunger assembly being movabletoward said one end of said cavity to compress a slurry in said pressingchamber vand drive fluid from the pressing chamber through said filterhead assembly,

means providing for loading of a slurry into said pressing chamber,

said die assembly having actuating chamber defining means rigidlyconnected with said cavity defining means and providing an actuatingchamber within said die assembly for containing fluid under pressureacting on said yplunger assembly to drive said plunger assembly towardsaid filter head assembly, and

means providing for delivery of fiuid under predetermined pressure tosaid actuating chamber to compress the slurry in said pressing chamberto a predetermined configuration,

said die assembly having a core member extending centrally of said diecavity, and electrical conductor means extending in said core member forthe length of said pressing chamber and closely adjacent thereto forproducing a magnetic orienting field in said pressing chamber.

5. The device of claim 4 with said cavity defining means and said coremember being of magnetic material, and said electrical conductor meansproviding for current flow in one direction at one diametric side ofsaid core member and providing for current flow in an opposite directionat an opposite diametric side of said core member.

6. A slurry pressing device comprising a die means having an open endand la closed end wall forming an elongated die cavity therebetween,

a core member mounted within said die cavity,

a filter head assembly for closing the open end of said cavity,

a free fioating plunger assembly mounted within said die cavity andslidably mounted on said core member,

said free lioating plunger assembly comprising a pressing piston means,an actuating piston means, and a connecting means interconnecting saidpressing and actuating piston means,

said pressing piston being in slidable contact with said core member andcavity walls,

one end of said pressing piston defining a movable boundary of a slurrypressing chamber formed between said pressing piston and said filterassembly when said filter assembly closes the cavity open end,

said connecting means being connected to the other end of said pressingpiston and spaced from the inner and outer side walls of said other endto form inner and outer .pressing piston perimeter-s,

first and second actuation chambers fonmed between said pressing pistonand said cavity closed end wall,

means communicating the actuation chambers with the pressing pistoninner and outer perimeters with one of said actuation chambers being incommunication with one end of the actuation piston and the otheractuation chamber being in communication with the other end of theactuation piston, and

means providing for delivery of fluid under predetermined pressure tosaid first and second actuating chambers to move said pressing pistontoward the filter assembly to compress a slurry in said pressing chamberto a predetermined configuration.

7. A slurry pressing device comprising a die means having an open endand a closed end wall forming an elongated die cavity therebetween,

a core member mounted within said die cavity,

a lter head assembly for closing the open end of said cavity,

a free fioating plunger assembly mounted within said die cavity andslidably mounted on said core member,

said free fioating plunger assembly comprising a pressing piston means,an actuating piston means, and a connecting means interconnecting saidpressing and actuating piston means, said pressing piston being inslidable contact with said core member and cavity walls,

one end of said pressing piston defining a movable boundary of a slurrypressing chamber formed between said pressing piston and said filterassembly when said filter assembly closes the cavity open end,

said connecting means being connected to the other end of said pressingpiston and spaced from the inner and outer side walls of said other endto form inner and outer pressing piston perimeters,

a first actuation chamber formed between one end of said actuationpiston, the cavity walls and said pressing piston means,

means communicating the first actuation chamber with the pressing pistonouter perimeter,

a second actuation chamber for-med between the other end of actuationpiston means and said cavity walls,

means communicating the second actuation chamber with the pressingpiston inner perimeter,

means providing for delivery of fluid under predetermined pressure tosaid first and second actuating chambers to move said pressing pistontoward the filter assembly to compress a slurry in said pressing chamberto a predetermined configuration.

8. A slur-ry pressing device comprising a die means having an open endand a closed end wall forming an elongated die cavity therebetween,

a core member centrally mounted within said die cavity,

a filter head assembly for closing the open end of said cavity,

a free oating plunger assembly mounted within said die cavity andslidably mounted on said core member,

said free floating plunger assembly comprising a pressing piston means,an actuating piston means, and a connecting means interconnecting saidpressing and actuating piston means,

said pressing piston being in slidable Contact with said core member andcavity walls,

one end of said pressing piston defining a movable boundary of a slurrypressing chamber formed between said pressing piston and said filterassembly when said filter assembly closes the cavity open end,

said connecting means being connected to the other end of said pressingpiston spaced from the inner and outer side walls of said other end toform inner and outer pressing piston perimeters,

said connecting means being spaced outwardly from the core member andinwardly from the cavity walls below said pressing piston,

said actuating piston being in slidable contact with said cavity walland spaced from said core member,

a first actuation chamber formed between said actuation piston, thecavity walls and said connecting means,

means communicating the first actuation chamber with the pressing:piston outer perimeter,

a second actuation chamber formed between the other end of saidactuation lpiston and said closed cavity end,

means communicating the second actuation chamber with the pressingpiston inner perimeter, and

means providing for delivery of fiuid under predetermined -pressure tosaid first and second actuating chambers to move said pressing pistontoward the filter assembly to compress a slurry in said pressing chamberto a predetermined configuration.

References Cited by the Examiner UNITED STATES PATENTS (Other referenceson following page) UNITED 1 5 STATES PATENTS Haller 18-16 XR Zink et a118-5 Schwable 18-5 Hunsdecker.

Haes etal.

16 FOREIGN PATENTS 35 2,433 1931 Great Britain.

I. SPENCER OVERHOLSER, Primary Examiner.

MICHAEL V. BRINDISI, Examiner.

1. A SLURRY PRESSING DEVICE COMPRISING A DIE ASSEMBLY HAVING CAVITYDEFINING MEANS PROVIDING AN ELONGATED DIE CAVITY OF A CROSS SECTIONALCONTOUR CORRESPONDING TO THE CROSS SECTIONAL CONTOUR OF A MASS TO BEFORMED, A FILTER HEAD ASSEMBLY FOR CLOSING SAID CAVITY AT ONE ENDTHEREOF, A FREE FLOATING PLUNGER ASSEMBLY HAVING PRESSING MEANS OF CROSSSECTIONAL CONTOUR MOVABLY FITTING IN SAID CAVITY OF SAID DIE ASSEMBLYAND HAVING ONE SIDE THEREOF DEFINING A MOVABLE BOUNDARY OF A SLURRYPRESSING CHAMBER OF SAID CAVITY AND SAID PLUNGER ASSEMBLY BEING MOVABLETOWARD SAID ONE END OF SAID CAVITY TO COMPRESS A SLURRY IN SAID PRESSINGCHAMBER AND DRIVE FLUID FROM THE PRESSING CHAMBER THROUGH SAID FILTERHEAD ASSEMBLY, MEANS PROVIDING FOR LOADING OF A SLURRY INTO SAIDPRESSING CHAMBER, SAID DIE ASSEMBLY HAVING ACTUATING CHAMBER DEFININGMEANS RIGIDLY CONNECTED WITH SAID CAVITY DEFINING MEANS AND PROVIDING ANACTUATING CHAMBER WITHIN SAID DIE ASSEMBLY FOR CONTAINING FLUID UNDERPRESSURE ACTING ON SAID PLUNGER ASSEMBLY TO DRIVE SAID PLUNGER ASSEMBLYTOWARD SAID FILTER HEAD ASSEMBLY, AND MEANS PROVIDING FOR DELIVERY OFFLUID UNDER PREDETERMINED PRESSURE TO SAID ACTUATING CHAMBER TO COMPRESSTHE SLURRY IN SAID PRESSING CHAMBER TO A PREDETERMINED CONFIGURATION,SAID ACTUATING CHAMBER DEFINING MEANS PROVIDING A SECOND ACTUATINGCHAMBER WITHIN SAID DIE ASSEMBLY FOR CONTAINING FLUID UNDER PRESSUREACTING ON SAID PLUNGER ASSEMBLY TO DRIVE SAID PLUNGER ASSEMBLY AWAY FROMSAID FILTER HEAD ASSEMBLY, THE AREA OF SAID PLUNGER ASSEMBLY EXPOSED TOFLUID PRESSURE IN SAID SECOND ACTUATING CHAMBER BEING SUBSTANTIALLY LESSTHAN THE AREA OF SAID PLUNGER ASSEMBLY EXPOSED TO FLUID PRESSURE IN THEFIRST-MENTIONED ACTUATING CHAMBER, AND SAID DELIVERY MEANS DELIVERINGFLUID UNDER SAID PREDETERMINED PRESSURE TO BOTH SAID FIRST MENTIONED ANDSAID SECOND ACTUATING CHAMBERS DURING PRESSING OF THE SLURRY IN SAIDPRESSING CHAMBER.